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/* This example was presented at the CNC'2 summer school on MPFR and MPC at |
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* LORIA, Nancy, France. It shows how one can use different rounding modes. |
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* This example implements the OddRoundedAdd algorithm, which returns the |
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* sum z = x + y rounded-to-odd: |
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* * RO(z) = z if z is exactly representable; |
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* * otherwise RO(z) is the value among RD(z) and RU(z) whose |
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* least significant bit is a one. |
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*/ |
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|
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/* |
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Copyright 2009-2020 Free Software Foundation, Inc. |
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Contributed by the AriC and Caramba projects, INRIA. |
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|
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This file is part of the GNU MPFR Library. |
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|
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The GNU MPFR Library is free software; you can redistribute it and/or modify |
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it under the terms of the GNU Lesser General Public License as published by |
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the Free Software Foundation; either version 3 of the License, or (at your |
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option) any later version. |
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|
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The GNU MPFR Library is distributed in the hope that it will be useful, but |
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
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License for more details. |
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|
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You should have received a copy of the GNU Lesser General Public License |
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along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see |
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https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., |
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51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. |
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*/ |
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|
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <gmp.h> |
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#include <mpfr.h> |
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|
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#define LIST x, y, d, u, e, z |
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|
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int main (int argc, char **argv) |
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{ |
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mpfr_t LIST; |
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mpfr_prec_t prec; |
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int pprec; /* will be prec - 1 for mpfr_printf */ |
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|
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if (argc != 4) |
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{ |
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fprintf (stderr, "Usage: rndo-add <prec> <x> <y>\n"); |
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exit (1); |
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} |
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|
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prec = atoi (argv[1]); |
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if (prec < 2) |
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{ |
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fprintf (stderr, "rndo-add: bad precision\n"); |
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exit (1); |
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} |
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pprec = prec - 1; |
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|
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mpfr_inits2 (prec, LIST, (mpfr_ptr) 0); |
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|
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if (mpfr_set_str (x, argv[2], 0, MPFR_RNDN)) |
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{ |
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fprintf (stderr, "rndo-add: bad x value\n"); |
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exit (1); |
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} |
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mpfr_printf ("x = %.*Rb\n", pprec, x); |
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|
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if (mpfr_set_str (y, argv[3], 0, MPFR_RNDN)) |
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{ |
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fprintf (stderr, "rndo-add: bad y value\n"); |
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exit (1); |
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} |
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mpfr_printf ("y = %.*Rb\n", pprec, y); |
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|
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mpfr_add (d, x, y, MPFR_RNDD); |
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mpfr_printf ("d = %.*Rb\n", pprec, d); |
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|
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mpfr_add (u, x, y, MPFR_RNDU); |
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mpfr_printf ("u = %.*Rb\n", pprec, u); |
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|
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mpfr_add (e, d, u, MPFR_RNDN); |
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mpfr_div_2ui (e, e, 1, MPFR_RNDN); |
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mpfr_printf ("e = %.*Rb\n", pprec, e); |
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|
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mpfr_sub (z, u, e, MPFR_RNDN); |
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mpfr_add (z, z, d, MPFR_RNDN); |
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mpfr_printf ("z = %.*Rb\n", pprec, z); |
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|
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mpfr_clears (LIST, (mpfr_ptr) 0); |
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mpfr_free_cache (); |
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return 0; |
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} |
